Year	Percent
1991	19.08429
1992	18.01652
1993	16.55018
1994	16.21995
1995	15.70393
1996	15.41153
1997	14.42143
1998	14.43855
1999	14.43143
2000	14.44
2001	13.60135
2002	13.5
2003	13.59864
2004	13.36
2005	13.15999
2006	12.84871
2007	12.31123
2008	11.71882
2009	11.1748
2010	10.60539
2011	10.26148
2012	9.98241
2013	9.4747
2014	9.40201
2015	9.37752
2016	9.4803
2017	9.25241
2018	9.21608
2019	8.96382